3 files changed, 72 insertions, 2 deletions

diff --git a/drivers/usb/host/xhci-pci.c b/drivers/usb/host/xhci-pci.c
index 85ffda8..e0a0a12 100644
--- a/drivers/usb/host/xhci-pci.c
+++ b/drivers/usb/host/xhci-pci.c
@@ -196,11 +196,15 @@ static void xhci_pci_quirks(struct device *dev, struct xhci_hcd *xhci)
 		xhci->quirks |= XHCI_BROKEN_STREAMS;
 	}
 	if (pdev->vendor == PCI_VENDOR_ID_RENESAS &&
-			pdev->device == 0x0014)
+	    pdev->device == 0x0014) {
 		xhci->quirks |= XHCI_TRUST_TX_LENGTH;
+		xhci->quirks |= XHCI_ZERO_64B_REGS;
+	}
 	if (pdev->vendor == PCI_VENDOR_ID_RENESAS &&
-			pdev->device == 0x0015)
+	    pdev->device == 0x0015) {
 		xhci->quirks |= XHCI_RESET_ON_RESUME;
+		xhci->quirks |= XHCI_ZERO_64B_REGS;
+	}
 	if (pdev->vendor == PCI_VENDOR_ID_VIA)
 		xhci->quirks |= XHCI_RESET_ON_RESUME;
 
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 02b5ea7..8c8da2d 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -209,6 +209,68 @@ int xhci_reset(struct xhci_hcd *xhci)
 	return ret;
 }
 
+static void xhci_zero_64b_regs(struct xhci_hcd *xhci)
+{
+	struct device *dev = xhci_to_hcd(xhci)->self.sysdev;
+	int err, i;
+	u64 val;
+
+	/*
+	 * Some Renesas controllers get into a weird state if they are
+	 * reset while programmed with 64bit addresses (they will preserve
+	 * the top half of the address in internal, non visible
+	 * registers). You end up with half the address coming from the
+	 * kernel, and the other half coming from the firmware. Also,
+	 * changing the programming leads to extra accesses even if the
+	 * controller is supposed to be halted. The controller ends up with
+	 * a fatal fault, and is then ripe for being properly reset.
+	 *
+	 * Special care is taken to only apply this if the device is behind
+	 * an iommu. Doing anything when there is no iommu is definitely
+	 * unsafe...
+	 */
+	if (!(xhci->quirks & XHCI_ZERO_64B_REGS) || !dev->iommu_group)
+		return;
+
+	xhci_info(xhci, "Zeroing 64bit base registers, expecting fault\n");
+
+	/* Clear HSEIE so that faults do not get signaled */
+	val = readl(&xhci->op_regs->command);
+	val &= ~CMD_HSEIE;
+	writel(val, &xhci->op_regs->command);
+
+	/* Clear HSE (aka FATAL) */
+	val = readl(&xhci->op_regs->status);
+	val |= STS_FATAL;
+	writel(val, &xhci->op_regs->status);
+
+	/* Now zero the registers, and brace for impact */
+	val = xhci_read_64(xhci, &xhci->op_regs->dcbaa_ptr);
+	if (upper_32_bits(val))
+		xhci_write_64(xhci, 0, &xhci->op_regs->dcbaa_ptr);
+	val = xhci_read_64(xhci, &xhci->op_regs->cmd_ring);
+	if (upper_32_bits(val))
+		xhci_write_64(xhci, 0, &xhci->op_regs->cmd_ring);
+
+	for (i = 0; i < HCS_MAX_INTRS(xhci->hcs_params1); i++) {
+		struct xhci_intr_reg __iomem *ir;
+
+		ir = &xhci->run_regs->ir_set[i];
+		val = xhci_read_64(xhci, &ir->erst_base);
+		if (upper_32_bits(val))
+			xhci_write_64(xhci, 0, &ir->erst_base);
+		val= xhci_read_64(xhci, &ir->erst_dequeue);
+		if (upper_32_bits(val))
+			xhci_write_64(xhci, 0, &ir->erst_dequeue);
+	}
+
+	/* Wait for the fault to appear. It will be cleared on reset */
+	err = xhci_handshake(&xhci->op_regs->status,
+			     STS_FATAL, STS_FATAL,
+			     XHCI_MAX_HALT_USEC);
+	if (!err)
+		xhci_info(xhci, "Fault detected\n");
+}
 
 #ifdef CONFIG_USB_PCI
 /*
@@ -1006,6 +1068,7 @@ int xhci_resume(struct xhci_hcd *xhci, bool hibernated)
 
 		xhci_dbg(xhci, "Stop HCD\n");
 		xhci_halt(xhci);
+		xhci_zero_64b_regs(xhci);
 		xhci_reset(xhci);
 		spin_unlock_irq(&xhci->lock);
 		xhci_cleanup_msix(xhci);
@@ -4917,6 +4980,8 @@ int xhci_gen_setup(struct usb_hcd *hcd, xhci_get_quirks_t get_quirks)
 	if (retval)
 		return retval;
 
+	xhci_zero_64b_regs(xhci);
+
 	xhci_dbg(xhci, "Resetting HCD\n");
 	/* Reset the internal HC memory state and registers. */
 	retval = xhci_reset(xhci);
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 2303ee4..939e2f86 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1841,6 +1841,7 @@ struct xhci_hcd {
 #define XHCI_HW_LPM_DISABLE	BIT_ULL(29)
 #define XHCI_SUSPEND_DELAY	BIT_ULL(30)
 #define XHCI_INTEL_USB_ROLE_SW	BIT_ULL(31)
+#define XHCI_ZERO_64B_REGS	BIT_ULL(32)
 
 	unsigned int		num_active_eps;
 	unsigned int		limit_active_eps;